You can unstuck yourself by hitting the "Unable to move" option here: https://eu.battle.net/support/en/help/product/wow/197/586After that, you can submit a bug report through the ingame option: http://eu.battle.net/support/en/article/reporting-a-bug

You probably meant a Demon Hunter, that and you've made a thread earlier which was answered here: https://eu.battle.net/forums/en/wow/topic/17624603711About Legion, everyone already has that included in the base game.

If you see other players on your realm other then the connected realms, it's probably crossrealmed players.For example, you could invite me to your realm from Ragnaros but I wouldn't be able to trade non-conjured items/join your guild etc while a connected realm player like Al'Akir and Skullcrusher can with Xavius realm players.